To enable the United States to become an adhering member of the Inter American Statistical Institute, there is hereby authorized to be appropriated annually, out of any money in the Treasury not otherwise appropriated, such sums as may be required for expenditure under the direction of the Secretary of State, for the payment of the share of the United States toward the support of the Institute: Provided, That (1) the membership dues of the United States payable for any fiscal year shall not be paid unless, during the preceding fiscal year, at least eight other American nations shall have been in good standing as adhering members, and unless at least eight of such other adhering members for the last preceding year for which such members were respectively obligated to pay dues shall have paid dues which aggregated at least $10,000, and (2) the total cost to the United States for any fiscal year, for adhering membership, shall not exceed $35,000.